The present invention relates to a semiconductor device which comprises a micromachine such as an optical switching device used for communication, measurement, or the like, and constructs a MEMS.
A MEMS (Micro Electro Mechanical Systems) having a micromachine formed by micropatterning has conventionally been known (see e.g., nonpatent references 1, 2, and 3). FIG. 20 shows an arrangement example of the MEMS. The MEMS shown in FIG. 20 comprises an electronic component 902 including at least one MEMS structure (micromachine) 901 formed by micropatterning, a control device 903 which generates a control signal for controlling the electronic component 902, and a control signal line 904 for supplying a control signal to the electronic component 902.
The control device 903 comprises a processor 905 which transmits predetermined control data and controls the operation of the MEMS structure 901, a memory 906 which holds the control program of the processor 905 and data necessary for the control program, an I/O 907 which inputs/outputs a signal outside the control device 903, a driving circuit 908 which generates a control signal to be supplied to the MEMS structure 901 on the basis of control data transferred from the processor 905, and a data bus 909 which connects the processor 905, memory 906, I/O 907, and driving circuits 908.
When the MEMS shown in FIG. 20 is, e.g., a MEMS optical switch, at least four control electrodes (not shown) are required to pivot a MEMS mirror (MEMS structure 901) on two axes, and control signals must be supplied from the driving circuit 908 to four control electrodes via four control signal lines 904. When the MEMS shown in FIG. 20 is, e.g., a MEMS mirror switch component in which 100 MEMS mirrors are mounted in an array, at least 400 driving circuits 908 and 400 control signal lines 904 are required. The driving circuit is generally comprised of a digital-to-analog converter (DAC) which converts a control signal into an analog signal, and an amplifier which amplifiers the output voltage of the DAC at a predetermined amplification factor. Mounting of driving circuits constituted by individual ICs requires many printed boards.
The above-mentioned prior arts are as follows:
“Optical Networking: MEMS Mirror Control”, ANALOG DEVICES, Searched Sep. 18, 2002, Internet <http://www.analog.com/productSelection/signalChains/communications/comms—17.html>
K. V. Madanagopal et al., “Real Time Software Control Of Spring Suspended Micro-Electro-Mechanical (MEM) Devices For Precision Optical Positioning Applications”, 2002 International Conference on Optical MEMs 2002, August, 2002, pp. 41–42
Hirao et al., “Circuit Design for High-Speed MEMS Mirror Drive”, 2002 IEICE Communications Society Conference, Sep. 11, 2002, p. 445
As described above, in a conventional MEMS, the control device becomes large even if a MEMS structure is manufactured with a small size. Also, many control signal lines which connect a MEMS structure and control device are necessary, and it is difficult to downsize the MEMS.